Forearm Flashcards
What type of scaphoid fracture are at risk of malunion/AVN
proximal fx
What is a Monteggia fracture?
proximal ulna fracture (of anterior angulation) resulting in radial head dislocation (often anterior)
complications of Monteggia fracture
radial nerve injury, compartment syndrome
nonunion, decreased ROM, etc
what is Galeazzi fracture?
distal 1/3 radial shaft fracture and distal radioulnar joint dislocation
What is the most common distal radius fracture
colles fracture
distal radius fracture with dorsal displacement (of distal bone fragment)?
colles fracture
distal radius fracture with volar displacement
smiths fracture
what part of carpal tunnel may compress on the median nerve
transverse carpal ligament
what are the contents of the carpal tunnel?
9 tendons - FDS (4), FDP (4), FPL
Median nerve
What is Kienbock’s disease?
avascular necrosis of the lunate
What test test for de quervain’s tenosynovitis
Finkelstein
pronator teres origin and insertion
O: medial epicondyle
I: lateral radius - middle 1/3
pronator teres innervation
median nerve
pronator teres action
pronate and flex forearm
what nerve is compressed in pronator syndrome
median nerve
flexor carpi radialis (FCR) origin and insertion
O: medial epicondyle
I: 2nd and 3rd metacarpal
FCR innervation
median nerve
FCR action
flex wrist
radial deviation
what muscle is the radial artery immediately lateral to?
FCR
palmaris longus origin and insertion
O: medial epicondyle
I: Flexor retinaculum/palmar aponeurosis
palmaris longus innervation
median nerve
palmaris longus action
flex wrist
what muscles tendon is commonly used for tendon transfers
palmaris longus
FCU origin and insertin
O: medial epicondyle and posterior ulna
I: pisiform, hook of hamate, 5th metacarpal
FCU innervation
ulnar nerve
FCU action
flex wrist, ulnar deviation
what is the most powerful wrist flexor
FCU
FCU may compress which nerve?
ulnar
FDS origin and insertion
O: 2 heads - humeroulnar and radial heads
- medial epicondyle and proximal ulna
- anteroproximal radius
I: Middle phalanges of digits (not thumb)
FDS innervation
median
FDS action
flex PIPJ (and flex digit and wrist)
FDP origin and insertion
O: anterior ulna and interosseous membrane
I: distal phalanx (IF, +/- MF, RF, SF)
FDP innervation
IF, +/- MF – median nerve/anterior interosseous nerve
+/- MF, RF, SF – ulnar nerve
FDP action
flex DIPJ (also flex digit and wrist)
what is jersey finger
avulsion of FDP from its distal insertion on the distal phalanx
FPL origin and insertion
O: anterior radius and proximal ulna
I: distal phalanx of thumb
FPL innervation
median n/AIN
FPL action
flex thumb
what does the AIN innervate
all three deep flexors (along with median nerve)
how do you test AIN function?
make okay sign
what muscules are most susceptible to Volkmann’s contracture
FDP and FPL
origin and insertion of pronator quadratus
O: medial distal ulna
I: anterior distal radius
pronator quadratus innervation
median nerve/AIN
pronator quadratus action
pronate forearm
primary pronator?
pronator quadratus
anconeus origin and insertion
O: posterior lateral epicondyle
I: posterior proximal ulna
anconeus innervation
radial nerve
anconeus action
forearm extension
extensor digitorum/extensor digitorum communis origin and insertion
O: later epicondyle
I: MCP - sagital band, P2 central slip, P3 terminal slip (digits 2-5)
extensor digitorum/extensor digitorum communis innervation
radial/PIN
extensor digitorum/extensor digitorum communis action
extend digits
boutonniere is caused by tendon avulsion of what muscle and where?
extensor digitorum/extensor digitorum communis at P2
mallet finger is caused by tendons avulsion of what muscle and where
extensor digitorum/extensor digitorum communis at P3
extensor digiti minimi (EDM) origin and insertion
O: lateral epicondyle
I: MCP - sagital band, P2 central slip, P3 terminal slip of digit 5 (small finger)
extensor digiti minimi (EDM) innervation
radial/PIN
extensor digiti minimi (EDM) action
little finger extension
extensor carpi ulnaris origin and insertion
O: lateral epicondyle
I: base of 5th MC
extensor carpi ulnaris innervation
radial/PIN
extensor carpi ulnaris action
hand extension and adduction
which muscle can cause painful snapping over the ulna
extensor carpi ulnaris
name the superficial extensors
aconeus
extensor digitorum communis
extensor carpis ulnaris
extensor digiti minimi
brachioradialis muscle origin and insertion
O: lateral condyle
I: lateral distal radius
brachioradialis innervation
radial
brachioradialis action
flex forearm
what muscle is a deforming force in radius fractures
brachioradialis
extensor carpi radialis longus action
wrist extension
extensor carpi radialis longus origin and insertion
O: lateral condyle
I: base of 2nd MC
extensor carpi radialis longus innervation
radial nerve
extensor carpi radialis brevis origin and insertion
O: lateral epicondyle
I: base of 3rd MC
extensor carpi radialis brevis innervation
radial nerve/PIN
extensor carpi radialis brevis action
wrist extension
what muscle tendon degenerates in tennis elbow?
extensor carpi radialis brevis
supinator origin and insertion
O: posterior medial ulna
I: proximal lateral radius
supinator innervation
radial/PIN
supinator action
forearm supination
abductor pollicis longus origin and insertion
O: posterior radius/ulna
I: base of 1st metacarpal
abductor pollicis longus innervation
radial/PIN
abductor pollicis longus action
abduct and extend thumb (CMCJ)
what tendon is affected in de Quervain’s disease
abductor pollicis longus
extensor pollicis brevis origin and insertion
O: posterior radius
I: base of thumb proximal phalanx
extensor pollicis brevis innervation
radial/PIN
extensor pollicis brevis action
extend thumb (MCPJ)
extensor pollicis longus origin and insertion
O: posterior ulna
I: base of thumb distal phalanx
extensor pollicis longus innervation
radial/PIN
extensor pollicis longus action
extend thumb (IPJ)
which tendon will turn 45 degrees as Lister’s tubercle
extensor pollicis longus
what muscles comprise superficial extensors
anconeus
extensor carpi ulnaris
extensor digiti minimi
extensor digitorum communis
extensor indices proprius origin and insertion
O: posterior ulna
I: MCP - sagital band, P2 - central slip, P3 - terminal slip
extensor indices proprius innervation
radial/PIN
extensor indices proprius action
extend index finger
What nerve provides sensory to the volar wrist capsule
AIN
What nerve provides sensory function to the posterior forearm?
radial nerve via the posterior cutaneous nerve of forearm
what does the PIN provide sensory function to?
dorsal wrist capsule
what nerve provides sensory function to the radial forearm?
musculocutaneous nerve (C5-C7) via lateral cutaneous nerve of forearm
what nerve provides sensory function to medial forearm?
medial cutaneous nerve of forearm (C8-T1)
What another name for ulnar tunnel
Guyon’s canal
What supplies the scaphoid? %?
Palmar scaphoid branch (from superficial palmar branch - which anastomoses with superficial palmar arch from radial artery) – supplies 25% of distal scaphoid
Dorsal scaphoid branch (from radial artery)– supples 75% of proximal scaphoid
signs of triangular fibrocartilage complex tear?
ulnar wrist pain
Pain worse with ulnar deviation
+Fovea sign - tenderness in the soft spot between the ulnar styloid and flexor carpi ulnaris tendon, between the volar surface of the ulnar head and the pisiform
How can TFCC tear occur
class 1 - traumatic (associated with ulnar styloid fx)
Class 2 - degenerative
how is TFCC tear treated
typically conservatively with NSAIDs and immobilization
In severe cases - repair/debride tear (traumatic) or ulnar shortening procedure
what is de quervain’s tenosynovitis
inflammation of the first dorsal compartment - APL/EPB
associated with tendon abnormality. Often occurs in middle aged women
treatment of de quervain’s tenosynovitis
- Splint and NSAIDs
- Corticosteroid injection into sheath
- Surgical release
most common area for ganglion cyst to occur
dorsal wrist - SL joint
Sites where median nerve compression can occur causing pronator syndrome
- Ligament of Struthers
- Pronator teres
- Bicipital aponeurosis
- FDS aponeurosis/arch
What is pronator syndrome
proximal median nerve compression
What is AIN syndrome
Rare nerve compression
same sites as pronator syndrome (ligament of struthers, pronator teres, FDS aponeurosis/arm, bicipital aponeurosis)
motor symptoms only
Symptoms/PE of AIN syndrome
Hx: weakness, +/- pain
PE: weak thumb (FPL) and index finger pinch (FDP)
Symptoms/PE of pronator syndrome
Hx: numbness, tingling, +/- weakness
PE: decrease palm sensation, + pronator or FDS sign
What is carpal tunnel associated with?
metabolic diseases - thyroid disease, diabetes, pregnancy
Hx and PE for carpal tunnel
numbness, +/- pain
PE: +/- thenar atrophy, + Tinel/Phalen/Durkin’s
Treatment for pronator/AIN syndrome
- Activity mod/rest
- NSAIDs, splinting
- Surgical decompression of all proximal sites
Treatment for carpal tunnel syndrome
- Activity modification
- NSAIDs, night splints
- Corticosteroid injections
- Surgical decompression
what is PIN syndrome and where can it occur?
Compression in radial tunnel
- fibrous bands
- leash of henry - aka recurrent radial artery
- extensor carpi radialis brevis
- Arcade of Frohse (proximal supinator edge)
5 Distal edge of supinator
Hx/PE for PIN syndrome
Hx: hand/wrist weakness, +/- elbow pain
PE : weak thumb/ finger extension; tenderness to palpation at radial tunnel
Workup for PIN syndrome?
XR: look for radiocapitellar abnormality
MR: evaluate for masses
EMG/NCS: confirms diagnosis and localizes lesions
treatment for PIN syndrome?
- activity mod
- NSAIDs/splints
- complete surgical decompression
How does radial tunnel syndrome differ from PIN syndrome?
Pain only, no weakness
How does AIN syndrome differ from pronator syndrome?
motor symptoms only (+/- pain)
What areas can cause radial tunnel syndrome
same as PIN syndrome:
- fibrous bands
- leash of henry - aka recurrent radial artery
- extensor carpi radialis brevis
- Arcade of Frohse (proximal supinator edge)
5 Distal edge of supinator
Work up for radial tunnel syndrome?
XR: evaluate RC joint
MRI: evaluate for masses
EMG/NCS: no useful
treatment for radial tunnel syndrome
- activity mod
- NSAIDs/splints
- complete surgical decompression
What is Wartenberg’s syndrome?
Compression of superficial radial nerve at the wrist between ECRB and BR tendons
sensory symptoms only
Hx/PE for Wartenberg’s syndrome
Hx: pain and paresthesias of the dorsoradial hand without motor symptoms
PE: decreases sensation at IF and thumb, +Tinel’s sign with pronation
workup for Wartenbergs syndrome
XR and MRI not helpful
EMG/NCS maybe helpful
treatment for Wartenbergs syndrome
- activity mod
- NSAIDs/splints
- complete surgical decompression
what is ulnar tunnel syndrome
Compression of the ulnar nerve at the ulnar tunnel (Guyon’s canal) located at the wrist
etiology of ulnar tunnel syndrome
- ganglion (MC)
- hamate malunion
- thrombotic artery
- muscle
Hx/PE of ulnar tunnel syndrome
Hx: Numbness, weakness in hand
PE: paresthesias and weakness of small finger and ring finger, +Tinel sign over Guyon’s canal
Treatment of ulnar tunnel syndrome
- activity mod
- NSAIDs/splints
- surgical decompression or address underyling cause (e.g. ganglion excision)
work up for ulnar tunnel syndrome
XR: look for fracture (hook of hamate) CT: for fx or malunion) MR: useful for masses US: evaluate for thrombosis EMG: confirms diagnosis
What is the name for instability within a carpal row (two types)
Carpal instability, dissociative (CID)
What are the two types of carpal instability dissociative
- Dorsal intercalated segment instability (DISI)
2. Volar intercalated segment instability (VISI)
etiology of dorsal intercalated segment instabiilty
- due to scapholunate ligament disruption or scaphoid fx/nonunion
- deformity: scaphoid flexes, lunate extends
- may lead to Scaphotrapeziotrapezoidal (STT) arthritis or scapholunate advanced collapse (SLAC)
What is etiology of volar intercalated segment instability?
- due to lunotriquetral ligament disruption (also requires dorsal radiocarpal ligament injury)
Hx for carpal instability dissociative?
Trauma, pain, +/- popping
PE findings for carpal instability dissociative?
+/- decreased ROM
+/- snuffbox or SL/LT interval tenderness, + Watson test (DISI) or Regan test (VISI)
Evaluation for carpal instability dissociative?
XR - wrist and clenched fist views
MRA - can confirm ligament injury
What would you see on XR in a DISI
SL gap > 3 mm
SL angle >70 degrees
“ring sign”
what would you see on XR in VISI
disrupted carpal arches
Treatment for CID
Acute/early
- Fx: ORIF of scaphoid
- Ligament: SL or LT ligament repair or reconstruction with pin fixation
- Capsulodesis
Chronic/Late
- Limited fusion
